imitator vs doer

imitator and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
imitator	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of imitator; that is, doer is a word with a broader meaning than imitator:

Other hypernyms of imitator include actor, worker.

imitator (noun)	doer (noun)
someone who copies the words or behavior of another	a person who acts and gets things done
someone who (fraudulently) assumes the appearance of another